Los Angeles -LRB- CNN -RRB- -- A former Los Angeles cop with military training vowed war against other men in blue Thursday , leaving one officer dead days after he allegedly killed two other people to begin a wave of retribution for being fired , police said .

The focus of the intensive , expansive manhunt is Christopher Jordan Dorner , a 270-pound former Navy lieutenant who has professed his venom against LAPD officers he claimed ruined his life by forcing him out of his dream job .

Dorner blames one retired officer for bungling his appeal to get his job back in an 11-page manifesto , in which he also complained of mistreatment by the LAPD . In that letter -- provided to CNN by an LAPD source -- he vowed to violently target police officers and their families , whoever and wherever they are .

`` I will bring unconventional and asymmetrical warfare to those in LAPD uniform whether on or off duty , '' Dorner wrote .

`` I never had the opportunity to have a family of my own , I 'm terminating yours . ''

Authorities believe he followed through on his threats early Thursday by shooting a Riverside , California , police officer and two others . A day earlier , Irvine police named Dorner a suspect in the double slayings Sunday of a woman -- identified by Los Angeles police as the daughter of a retired LAPD officer -- and her fiance .

`` My opinion of the suspect is unprintable , '' said Riverside police Chief Sergio Diaz , hours after one of his officers was killed . `` The manifesto , I think , speaks for itself -LRB- as -RRB- evidence of a depraved and abandoned mind and heart . ''

The violence , as well as Dorner 's background as a police officer and military trained marksman , left police on edge around Southern California .

In Torrance , LAPD officers guarding one of Dorner 's alleged targets mistakenly opened fire on a blue pickup truck that resembled one Dorner was thought to be driving , said Los Angeles police Chief Charlie Beck .

The gunfire left two people wounded , Beck said . Torrance police also fired on another blue pickup , but no one was injured in that incident , according to a senior law enforcement source .

In downtown Los Angeles , police wearing body armor patrolled outside their own iconic headquarters .

Police have good reason to be fearful , the chief said .

`` Of course , he knows what he 's doing . We trained him , '' Beck said . `` He was also a member of the armed forces . It is extremely worrisome and scary , especially to the officers involved . ''

The manhunt for Dorner spanned hundreds of miles and numerous counties . By Thursday afternoon , it was largely centered around Big Bear Lake -- about 100 miles east of Los Angeles -- where authorities found the truck the suspect allegedly used in the Riverside shooting .

KTLA : Manhunt for former cop after officers shot

Police confirmed that the vehicle , which was burnt out when it was found , belonged to Dorner by its vehicle identification number , San Bernardino County Sheriff John McMahon said .

This discovery spurred more officers to converge on the area to conduct beefed up patrols , staff checkpoints and go to every residence in the mountain community . McMahon acknowledged the fire may have been set as a diversionary tactic , though law enforcement is n't taking any chances . Early Thursday evening , he said that aerial and K9 searches on the ground will `` continue as long as we can '' -- though snow is coming -- and urged locals to be on alert .

`` He could be anywhere at this point , and that 's why we 're searching door to door , '' the sheriff said .

1 cop dies in ` cowardly ambush '

It all started Sunday when Dorner allegedly killed two people in Irvine , according to police .

Police identified the victims as Monica Quan and her fiance Keith Lawrence .

Quan , 27 , was the daughter of retired Los Angeles police Officer Randal Quan , LAPD Officer Tenesha Dobine told CNN . In his manifesto , Dorner said Quan handled his appeal .

On Tuesday , Dorner checked into the Navy Gateway Inns and Suites on San Diego 's large naval base , Cmdr. Brad Fagan said .

Dorner likely had access to the hotel because he 'd been honorably discharged from the Navy Reserve , said the Navy spokesman . Having retired February 1 as a lieutenant , Dorner worked with mobile inshore undersea warfare units and provided security on oil platforms in Iraq , according to Pentagon records . He was rated as a rifle marksman and pistol expert .

`` He did not physically check out '' Wednesday as expected , Fagan told reporters .

Police in San Diego say a man who could have been Dorner tried to hijack a boat there on Wednesday . Someone later found a wallet containing Dorner 's identification and an LAPD detective 's badge near the San Diego airport , according to police . It was unclear whether the badge was legitimate .

Timeline in manhunt for former L.A. cop

By about 1 a.m. Thursday , the scene had shifted about 100 miles north to Corona , California .

There , a pair of LAPD officers on a protection detail were flagged down by a citizen who reported seeing the suspect 's vehicle , LAPD Deputy Chief Jose Perez said .

The officers chased the vehicle and caught up to it on an Interstate 15 off-ramp .

`` The officers were fired upon with a shoulder weapon , '' Perez said , with one of them suffering a `` graze wound '' to his head . The police returned fire , while the suspect set off once again .

About 20 minutes later , two police officers were in their car at a stop light in Riverside when Dorner allegedly pulled up beside them .

That driver unleashed `` multiple rounds '' from a rifle at the officers , riddling the cop car with bullets and leaving a 34-year-old officer , who had been on the Riverside force for 11 years , dead , according to Diaz . The other officer , 27 , was `` seriously wounded but we expect a full recovery , '' the Riverside police chief said .

KCBS : Riverside officer fatally shot

It was `` a cowardly ambush , '' said Diaz , claiming Dorner has `` no connection '' to his city .

A good Samaritan picked up one of their police radios and called dispatchers to send help , Riverside police said .

Suspect calls attacks ' a necessary evil '

In addition to posting his manifesto online , Dorner reached out directly to CNN , mailing a parcel to AC360 anchor Anderson Cooper 's office at CNN in New York .

The package arrived on February 1 and was opened by Cooper 's assistant . Inside was a hand-labeled DVD , accompanied by a yellow Post-it note reading , in part , `` I never lied '' -- apparently in reference to his 2008 dismissal from the LAPD .

The package also contained a coin wrapped in duct tape . The tape bears the hand-written inscription : `` Thanks , but no thanks , Will Bratton . '' It also had letters that may be read as `` IMOA '' , which could be a commonly used Internet abbreviation for `` Imagine a More Open America , '' or possibly `` 1 MOA , '' which means one minute of angle , perhaps implying Dorner was notably accurate with a firearm .

The coin is a souvenir medallion from former LAPD Chief William Bratton , of a type often given out as keepsakes . This one , though , was shot through with bullet holes : three bullet holes to the center and another shot nicked off the top .

The editorial staff of AC360 and CNN management were made aware of the package Thursday . Upon learning of its existence , they alerted Bratton and law enforcement .

Bratton headed the LAPD at the time Dorner was dismissed .

The dispute centers on a 2007 incident in San Pedro involving a man 's arrest at a DoubleTree hotel . Two weeks later , Dorner accused his training officer of kicking the man after he 'd given up .

The investigators ' report said `` the delay in reporting the alleged misconduct coupled with the witness ' statements irreparably destroy Dorner 's credibility . '' The report cited contradictory accounts from the arrested man and his father and denials by the accused officer and three hotel employees that the arrested man had been kicked . Dorner claims he was wrongly ousted for blowing the whistle on what he insists was police abuse .

Suspect 's grudge dates back to 2007 complaint

Dorner challenged his firing for years , losing at every turn . First , the police department 's Board of Rights rejected his appeal . Then , in October 2011 , a judge ruled against his appeal , according to court records .

Beck , the Los Angeles police chief , said Thursday that Dorner 's case had been `` thoroughly reviewed '' and said the department would not apologize to Dorner or clear his name .

But as his manifesto shows , Dorner is showing no sign of relenting .

He complained he had been railroaded out of the department after reporting police brutality by another officer . Dorner also complained of a continuing culture of racism and brutality in the LAPD .

Attacks on other police officers and their families , he said , are `` a necessary evil that I do not enjoy but must partake and complete for substantial change to occur within the LAPD and reclaim my name . ''

`` Look your wives/husbands and surviving children directly in the face and tell them the truth as to why your children are dead , '' Dorner wrote .

Such a chilling warning prompted Los Angeles police to set up 40 protective details in an effort to safeguard people listed in Dorner 's letter , Beck said .

The chief acknowledged that this effort was taxing the department , which has been placed under tactical alert , meaning all officers must stay on duty .

`` It 's extremely , extremely manpower intensive , '' Beck said . `` But the safety of my employees , people that come on the job to protect the lives of strangers , is extremely important to me . And I will expend whatever resource is necessary . ''

KABC : Former cop shoots three officers

CNN 's AnneClaire Stapleton , Sara Weisfeldt , Barbara Starr , Pete Janos , Mallory Simon and Deanna Hackney contributed to this report .

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NEW : With snow coming , authorities continue to hunt for the suspect near Big Bear Lake

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Police believe former cop Christopher Jordan Dorner shot three officers , killing one

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This was days after he allegedly killed two people , one a retired LAPD officer 's daughter

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In an 11-page manifesto , Dorner promises `` war '' on police and their families